Publish an audio-only stream (HLS)

[nnmk]

Hi,

the documentation says this:

"To serve streams over a cellular network, one of the streams must be audio-only. For more information, see HTTP Live Streaming Overview.

To publish an audio-only stream, enter the following in the Flash Media Encoder Stream field:

livestream%i?adbe-live-event=liveevent&adbe-audio-stream-name=livestream1_audio_only&adbe-audio-stream-src=livestream1

If the encoder specifies individual query strings for each stream, use individual stream names instead of the variable %i:

livestream1?adbe-live-event=liveevent&adbe-audio-stream-name=livestream1_audio_only

livestream2?adbe-live-event=liveevent&adbe-audio-stream-name=livestream2_audio_only

"

...

"

To generate a set-level variant playlist when using an audio-only stream, specify the audio codec of the audio-only stream. Specify the audio and the video codec of the streams that contain audio and video. For more information about using the Set-level F4M/M3U8 File Generator, see Publish and play live multi-bitrate streams over HTTP.

"

Does this mean that using one FMLE encoder (with the installed AAC plugin) i can stream BOTH audio+video AND audio only stream via HLS to iOS clients?

If yes, how to connect to a+v stream and how to connect audio only stream in iOS  ? (To be more precise - i would need two m3u8 files, how do i create them in the provided generator)

What about the need to provide multiple bitrates (for the audio), surely 64 isn't enough - multiple encoder machines or multiple encoder instances?

[NpComplete · Accepted solution]

Does this mean that using one FMLE encoder (with the installed AAC plugin) i can stream BOTH audio+video AND audio only stream via HLS to iOS clients?

yes

If yes, how to connect to a+v stream and how to connect audio only stream in iOS  ? (To be more precise - i would need two m3u8 files, how do i create them in the provided generator)

In this case, ios can play a+v stream using m3u8 url

http://server/hls-live/livepkgr/_definst/liveevent/livestream1.m3u8

and audio-only stream using m3u8 url

http://server/hls-live/livepkgr/_definst_/liveevent/livestream1_audio_only.m3u8

Using the generator you can create a variant playlist where you can specify multiple bitrate a+v streams m3u8 url (that you already know) and audio only stream m3u8 url. This tool is just a serialiser of all the information that you provide to it. It doesn't generate individual streams m3u8 urls on it's own. This variant playlist can be hosted somewhere. When player request this variant playlist, it identifes all the bitrate and corresponding m3u8 urls. Player will then play the m3u8 url that hasbitrate just less than to its input bandwidth.

Probably I couldn't get your question clearly. Let me know if it helps.

[nnmk]

Thank you sir.

[nnmk]

What about the need to provide multiple bitrates (for the audio), surely 64kbps isn't enough (64 is needed as per apple documentation) - multiple encoder machines or multiple encoder instances, how to provide multiple audio bitrate?

(surely we also need a better quality for the streamed audio but also need the 64)

[NpComplete]

You are right. You don't need to provide multiple bitrate audio in the variant playlist. So while specifying on FMLE

livestream%i?adbe-live-event=liveevent&adbe-audio-stream-name=livestream1_audio_only&adbe-audio-stream-src=livestream1

set adbe-audio-stream-src to such a  a+v stream that that audio bitrate of 64 kbps.

This will create 4 streams for you on FMS

livestream1, livestream2, livestream3, livestream1_audio_only

On encoders other than FMLE, where it is not supported to publish multiple streams with a single publish option, you may publish

1. livestream1?adbe-live-event=liveevent&adbe-audio-stream-name=livestream1_audio_only

2. livestream2?adbe-live-event=liveevent

3. livestream3?adbe-live-event=liveevent

This will create 4 streams for you on the FMS

livestream1, livestream2, livestream3, livestream1_audio_only

Yes, there is no point publishing audio only live stream corresponding to each a+v stream. Apple spec mandates only one audio only stream of 64kbps in variant playlist

[nnmk]

Of course, but what if we need lets say 128kbs AND 64kbps audio ?

[nnmk]

Let me just confirm that the above works and correct a couple of typos in streaming links for the iOS:

A+V stream:

http://server/hls-live/livepkgr/_definst_/liveevent/livestream1.m3u8

Audio only stream:

http://server/hls-live/livepkgr/_definst_/liveevent/livestream1_audio_only.m3u8

Thanks again Nitin, if you could just comment on how to achieve audio with two different bitrates on the encoder side when you get the time.

[NpComplete]

Hi nnmk,

Though I am no expert in FMLE, but just try

livestream%i?adbe-live-event=liveevent&adbe-audio-stream-name=livestream%i_audio_only&adbe-audio-stream-src=livestream%i

I assume, FMLE will replace all %i to numbers (not just %i in actual stream name)